[英]How to get grayscale value of a pixel in OpenCV for Android
I want to get the gray scale value of a pixel in OpenCV for Android. 我想在Android的OpenCV中获取像素的灰度值。 The problem is that OpenCV for Android is very much undocumented and a lot of the methods are different.
问题在于,Android的OpenCV尚未公开,许多方法有所不同。 I have found answers to this problem, but none of them work for android.
我已经找到了解决此问题的方法,但是它们都不适合android。
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.SurfaceView;
import android.hardware.camera2.CameraCaptureSession;
import org.opencv.android.BaseLoaderCallback;
import org.opencv.android.CameraBridgeViewBase;
import org.opencv.android.CameraBridgeViewBase.CvCameraViewListener2;
import org.opencv.android.JavaCameraView;
import org.opencv.android.LoaderCallbackInterface;
import org.opencv.android.OpenCVLoader;
import org.opencv.core.Mat;
public class testActivity extends AppCompatActivity implements CvCameraViewListener2 {
private BaseLoaderCallback mLoaderCallback = new BaseLoaderCallback(this) {
@Override
public void onManagerConnected(int status){
switch (status){
case LoaderCallbackInterface.SUCCESS:
{
mOpenCvCameraView.enableView();
break;
}
default:
{
super.onManagerConnected(status);
}
}
}
};
private JavaCameraView mOpenCvCameraView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_test);
mOpenCvCameraView = (JavaCameraView) findViewById(R.id.testVideoView);
mOpenCvCameraView.setMaxFrameSize(240,320);
mOpenCvCameraView.setVisibility(SurfaceView.VISIBLE);
mOpenCvCameraView.setCvCameraViewListener(this);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
//getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
getSupportActionBar().hide();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
public void onDestroy() {
super.onDestroy();
if (mOpenCvCameraView != null)
mOpenCvCameraView.disableView();
}
public void onResume(){
super.onResume();
if (!OpenCVLoader.initDebug()) {
OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_2_4_9, this, mLoaderCallback);
} else {
mLoaderCallback.onManagerConnected(LoaderCallbackInterface.SUCCESS);
}
}
@Override
public void onPause() {
super.onPause();
if (mOpenCvCameraView != null)
mOpenCvCameraView.disableView();
}
@Override
public void onCameraViewStarted(int width, int height) {
}
@Override
public void onCameraViewStopped() {
}
@Override
public Mat onCameraFrame(CameraBridgeViewBase.CvCameraViewFrame inputFrame) {
return inputFrame.gray();
}
}
I'll assume you mean "how to extract gray pixel from RGB Mat", because getting the gray pixel from Mat that represents a grayscale image is trivial. 我假设您的意思是“如何从RGB Mat中提取灰度像素”,因为从Mat中获取代表灰度图像的灰度像素是微不足道的。
What you can do is define submat of size 1x1 for instance 您可以做的是例如定义大小为1x1的子垫
Mat bgrPixel= rgbMat.submat(x,y,x,y).clone();
Mat grayPixel = new Mat(1,1, CvType.CV_8UC1);
Imgproc.cvtColor(bgrPixel, grayPixel, Imgproc.COLOR_BGR2GRAY);
(maybe the indexes are x,y,x+1,y+1, I'm not sure) after that you can use your gray pixel. (也许索引是x,y,x + 1,y + 1,我不确定),之后您就可以使用灰色像素了。
It's not an elegant solution but it should work. 这不是一个优雅的解决方案,但它应该可以工作。
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